| 荒漠地区包气带氯离子与硝酸盐的空间分布特征 |
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| 引用本文： | 张金,付素静,王云权,马金珠. 荒漠地区包气带氯离子与硝酸盐的空间分布特征[J]. 干旱区地理, 2013, 36(3): 409-415 |
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| 作者姓名： | 张金 付素静 王云权 马金珠 |
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| 作者单位： | （1 兰州大学资源环境学院， 甘肃 兰州 730000； 2 河北省环境科学研究院环境规划所， 河北 石家庄 050000；3 兰州大学西部环境教育部重点实验室，西部环境与气候变化研究院， 甘肃 兰州 730000） |
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| 基金项目： | 国家创新群体科学研究基金项目，科技部"973"项目的课题 |
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| 摘 要： | 荒漠地区包气带中的Cl-、NO3-与生态环境有密切联系，与地下水安全有直接联系。主要以荒漠地区包气带Cl-、NO3-为研究对象，通过对Cl-、NO3-在包气带及不同土壤类型中的分布特征进行研究，表明强烈的蒸散发作用使Cl-、NO3-呈活塞式分布，同时植物对水分的吸收以及对NO3-的优先吸收使NO3-表现出不同的分布特征。土壤中的NO3-可能被植物优先吸收并遵循营养循环，使表层土壤中出现极大值，随后逐渐减小。靠近表层土壤出现NO3-峰值和较高的NO3-/Cl-原子比率反映了蓝藻菌活跃的固N作用；相对较大的NO3-/Cl-原子比率伴随着较低的Cl-说明在干旱地区稀疏的植被覆盖条件限制了对NO3-的吸收作用。不同的土壤类型中，Cl-、NO3-表现出不同的分布特征，在粘性土壤中，NO3-、Cl-浓度随含水率的减小而减小。
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| 关 键 词： | 荒漠地区 Cl- NO3- NO3-/Cl- 沙漠包气带水分 |
| 收稿时间： | 2012-08-10 |
Spatial distribution of chloride and nitrate in the desert areas |
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| ZHANG Jin,FU Su-jing,WANG Yun-quan,MA Jin-zhu. Spatial distribution of chloride and nitrate in the desert areas[J]. Arid Land Geography, 2013, 36(3): 409-415 |
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| Authors: | ZHANG Jin FU Su-jing WANG Yun-quan MA Jin-zhu |
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| Affiliation: | （1 Earth and Environmental Sciences，Lanzhou university，Lanzhou 730000，Gansu, China; 2 Hebei Research Academy of Environmental Sciences；Shijiazhuan 050000, Hebei, China; 2 Key Laboratory of Western China Environmental Systems（MoE），Lanzhou University，Lanzhou 730000，Gansu, China） |
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| Abstract: | Chloride and nitrate，as a conservative and a semi-conservative ion，have been used to examine the recharge history, reconstruct the related climate change and vegetation transitions and so on in the cold-arid desert region of northwest China. In general，they always transport with rainfall in the soil，even though the nitrate always takes part in plenty of bio-chemical reactions. And soils are crucial to the functioning of the Earth system, since they are at the interface between the atmosphere，lithosphere，hydrosphere and biosphere，and influence terrestrial net primary production, climate regulation, and water quality. So revealing the spatial distribution of the dissolved chloride and nitrate is favor to prohibit the potential water contamination caused by nitrate leaching from upwards, and to understand the impacts on the desert ecosystem. The water content and nitrate and chloride concentrations with the NO3-/Cl- were measured in different profiles and different soil types in verticality. It was found that the distributions of Cl-、NO3- tend to be piston oscillations as a result of the severe evapotranspiration. The average concentrations of Cl- increase from 35 mg/L to 6 545 mg/L，with the maximum rising from 41 mg/L to 9 592 mg/L，correspondingly. Meanwhile，the average concentrations of NO3- range from 8 mg/L to 1 227 mg/L，and the average NO3-/Cl- molar ratios are between 0.03 and 1.75. The relatively higher NO3- concentration in Wuwei and Minqin areas，especially in the profiles WW1、WW3、MQ1, may demonstrate the effects of the anthropogenic inputs. And the declines of the NO3-/Cl- molar ratios from east to west may be due to the decrease of the rainfall from southeast to northwest in the area. Plant’s taking-up of moisture and nitrate preferentially makes the nitrate distribute differently in vadose zone. The presence of peaks in the nitrate profiles is probably proportional to the preferential taking-up of nitrate and due to be coincidence with the nutrient profile，which leads the concentration of nitrate to decline sharply with the soil depth. The near surface peaks in NO3- with higher NO3-/Cl- molar ratios reflect active modern N-fixation by cyanobacteria. The higher NO3-/Cl- molar ratios are consistent with the bulge shaped Cl-，which probably indicates that relatively less vegetation coverage in the drought environment plays a limiting role in the uptake of nitrate. The characteristics of chloride and nitrate tend to be distinct in different soil types .The piston distribution of chloride and nitrate in the sand soil，which has a great conductivity and inferior water binding capacity, attributes to the plant taking in the nitrate within its cycling in the soil along with intensive evapotranspiration，while the concentration of chloride and nitrate in the clay soil decreases with the moisture content. |
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| Keywords: | desert areas chloride nitrate NO3-/Cl-molar ratios soil moisture |
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